Refrigeration system with means for controlling oil return



REFRIGERATION SYSTEM WITH MEANS FOR CONTROLLING OIL RETURN Filed Sept. 29, 1966 GA/THEF? 5- GARNER IN VEN TOR.

ATTORNEY.

United States Patent 0 3,379,030 REFRIGERATIGN SYSTEM WETH MEANS FOR CONTROLLING 01L RETURN Gaither B. Garner, 2325 Ridge Road, Raleigh, NC. 2766, Filed Sept. 29, 1966, Ser. No. 582,975 7 Claims. ((Jl. 6212) This invention relates to refrigeration systems and more particularly to suction line evaporators to separate compressor lubricant from refrigerant and to prevent liquid refrigerant from entering the suction side of the compressor of a refrigeration system.

The presence of any liquid refrigerant in the crankcase of a refrigeration compressor causes the oil to expand to such proportions that a check of the oil level will indicate an erroneous level which in extreme cases can very badly damage or completely ruin a compressor. Also if some of the liquid refrigerant which is suppose to evaporate into a gaseous state in the refrigeration evaporator does not so evaporate, and enters the suction or low side of the compressor as a liquid, substantial damage may be caused to the unit.

In the past, various devices have been devised in attempts to separate oil from refrigerant as well as various means for preventing what is commonly known as slugover or liquid refrigerant entering the suction side of the compressor. With advent of large refrigeration systems for buildings, food storage areas and the like, it has become extremely important to prevent any damage to the compressor and to keep it operating properly due to the very great cost of repairing and replacing these units as well as the inconveniences caused by their breakdowns.

The present invention has been developed after much research and study of the above mentioned problems and is designed to overcome them by providing a refrigeration system which uses the natural heat created by the refrigeration process to completely evaporate all refrigerant prior to its entering the compressor. The utilization of this heat also serves the dual function of separating liquid refrigerant from compressor lubricant thereby completely preventing indications of a higher oil level than is actually available. Applicants invention does not leave the control of the system to manual operation or fixed automatic feed-back as some of the prior art devices have taught, but automatically controls the suction line evaporator so that no lubricant or oil will be returned to the crankcase of the compressor until all liquid refrigerant has been evaporated. The oil line will then open and remain open so long as there is no liquid refrigerant in the evaporator. Should liquid refrigerant enter the evaporator, means are provided for automatically closing the oil line return.

It is, therefore, an object of the present invention to provide a suction line evaporator having means for automatically separatin compressor lubricants from refrigerants and independently passing these products to their predesignated inlet areas of the compressor in a refrigeration system.

Another object of the present invention is to provide a suction line evaporator utilizing the natural heat created by the operation of the refrigeration system to operate such evaporator.

A further object of the present invention is to provide a means in a suction line evaporator to automatically release accumulated compressor lubricant into the crankcase of the refrigeration compressor whenever no liquid refrigerant remains in such evaporator.

Another object of the present invention is to provide a suction line evaporator composed of an enclosed barrel having a suction line intake operatively connecting it to the evaporator of a refrigeration system, an exhaust suction line operatively connected to the suction side of a refrigeration compressor, a lubricant return line operatively connected to the crankcase of such compressor and automatically operated means for separating and transferring refrigerants and lubricants to said suction side and crankcase respectively.

Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of the present invention.

In the drawings:

FIG. 1 is a diagrammatic view of a refrigeration system having the present invention integrated thereinto; and

FIG. 2 is an enlarged diagrammatic view of the suction line evaporator of the present invention.

With further reference to the drawings, FIG. 1 discloses a refrigeration system including a compressor 10 having a high pressure hot gas line 11 leading from the head thereof into the upper portion of enclosed jacket 12 which encircles the suction line evaporator indicated generally at 14. A high pressure exhaust line 15 is connected adjacent the lower portion of heating jacket 12 and operatively connects said jacket with condenser 16 which in turn is operatively connected to receiver 17 in the normal fashion. Liquid refrigerant line 18 is provided which allows the liquefied refrigerant to pass from receiver 17 to cooling evaporator coils 19. A thermostatically control expansion valve is provided in liquid line 18 to control the amount of liquid refrigerant entering evaporator 19. Other devices for controlling the amount of liquid refrigerant passing into the evaporator, such as the well known capillary tube, could be substituted for valve 26.

Liquid refrigerant suction line 21 is provided between evaporator 19 and the enclosed upper end 23 of this suction line 21 projects into barrel 22 a greater distance than the intake end of compressor suction line 24 which connects evaporator 14 to compressor 10.

At the opposite end of barrel 22 from upper end portion 23 is lower end portion 25 to which oil return line 26 is connected. The other end of line 26 communicates with the oil reservoir portion of the crankcase of compressor 10. Mounted intermediate the ends of oil or lubricant return line 26 is a solenoid operated valve 27 which is operated by means of thermostat control 28 which is activated by liquid filled bulb 29, preferably mounted on the lower exterior surface of barrel 22 below heat jacket 12.

In actual operation of a refrigeration system incorporating the present invention, compressor Ill compresses the gaseous refrigerant and forces it to pass through line 11 into the upper portion of heating jacket 12. This hot gas then passes around and in contact with the exterior of inner barrel 22 thereby warming it to a temperature near that of the now compressed refrigerant. The refrigerant then leaves the lower portion of jacket 12 and enters condenser 16 from whence it passes into receiver 17 by which time the refrigerant is liquefied.

The liquid refrigerant from receiver 17 passes through line 18, through thermostatically controlled expansion valve 20, and on into evaporator coil 19. As the liquid refrigerant expands in coils 19 thereby cooling the same, the liquid refrigerant vaporizes. The vaporized refrigerant then passes through line 21 into evaporator 14. Any unevaporated refrigerant as well as compressor crankcase lubricant also passes through line 21 into evaporator 14.

So long as any liquid refrigerant remains inside barrel 22, the temperature in the lower portion thereof which is not surrounded by heating jacket 12 will remain at a relatively low temperature. Since jacket 12 heats the interior of barrel 22, the liquid which by gravity falls in the lower portion of such barrel will evaporate. Once evaporated, it will pass through suction line 24, along with the vaporized refrigerant which has come through line 21 from evaporator 19, into the low pressure side of compressor 1.0.

Once all of the liquid refrigerant has been evaporated from the lower portion of barrel 22, the interior of th barrel and the exterior of the lower portion thereof will rapidly rise in temperature due to the warming effect of the compressed gas passing through jacket 12. Case the predetermined temperature is reached, liquid filled sensing bulb 29 causes thermostat 28 to open solenoid valve 27 thereby allowing any accumulated oil or crankcase lubricant in the lower portion of barrel 22 to gravity feed into the crankcase of compressor 19. This valve wil remain open until liquid refrigerant passes through line 21 into barrel 22 which will intcrmediately drop the temperature in a lower portion of such barrel thereby causing temperature sensing bulb 29 through thermostat control 2% to close solenoid valve 27.

It has been found in actual operation of the present invention that a liquid filled bulb 29 is usually preferred since it is not readily affected by temperature changes in the ambient air.

The thermostat control 28 should be set for approximately two degrees differential between the opening and closing of solenoid valve 27. In other words, a two degree drop in temperature sensed by bulb 29 should close valve 27. It has been found through experience that a setting of thermostat control 28 to operate at approximately to degress above the ambient air gives satisfactory results.

It is obvious that the present invention has the advantage of providing a completely reliable, automatically controlled means for preventing liquid from entering the suction side of a refrigerationcompressor as well as preventing expanded oil levels in the compressor crankcase due to the mixing of refrigerants with the oil.

The terms upper, lower, bottom, top and so forth have been used herein merely for convenience in the foregoing specification and in the appended claims to describe the refrigeration system and its parts as oriented in the drawings. It is to be understood, however, that these terms are no way limiting to the invention since the system may obviously be disposed in many different positions when in use.

The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. In a refrigeration system having a compressor with high pressure and low pressure sides and a crankcase, a high pressure line for conveying gases from the high pressure side to a condenser, a receiver to collect liquefied refrigerant in operative relation to said condenser, an evaporator for vaporizing said liquid refrigerant in operative relation to said receiver, and a suction line operatively connected from said evaporator to the low pressure side of said compressor; the improvement comprising: a suction line evaporator composed of an enclosed inner barrel having upper and lower portions; said suction line passing from said evaporator into the upper portion of said barrel; said suction line leaving the upper portion of said barrel and passing into the suction side of said compressor; a

lubricant return line passing from the lower portion of said barrel to the crankcase of said compressor; an enclosed jacket having upper and lower portions surrounding a substantial portion of the exterior of said barrel; said high pressure line passing from the high pressure side of said compressor to the upper portion of said jacket; said high pressure line leaving the lower portion of said jacket and connected to said condenser; temperature sensing means located adjacent the lower portion of said barrel; thermostatic control means operativeiy connected to said casing means; and a valve means located in said lubricant e and controlled by said thermostat whereby by means of temperature sensing an automatic valve control, liquid refrigerants and crankcase lubricants may be separated and passed to their respective inlets in said compressor.

2. In a refrigeration system having a compressor with a high pressure outlet, a low pressure suction inlet, a lubricant inlet, and a condenser operatively connected to an evaporator, the improvement comprisin a suction line evaporator composed of an enclosed cylindrical barrel having upper and lower portions; an enclosed cylindrical jacket mounted about said barrel and covering a substant al portion thereof; a high pressure line operatively connected from said high pressure outlet to said jacket; a high pressure exhaust line operatively connected from said jacket to said condenser; an evaporator suction line operatively connected from said evaporator to said barrel; a compressor suction line operatively connected from the upper portion of said barrel to the suction inlet of said compressor; a lubricant return line operatively connected from the lower portion of said barrel to said lubricant inlet; and automatic valve means operatively mounted in said lubricant line whereby when the temperature in said barrel reaches a predetermined temperature which assures that any liquid refrigerant which has passed into said barrel has vaporized, said valve will open allowing any compressor lubricant which has accumulated in the lower portion of said barrel to pass into the lubricant inlet of said compressor.

3. The system of claim 2 in which the automatic valve means comprises a temperature sensing element; said element being secured to the lower portion of said barrel; a thermostatic control means operatively connected to said sensing element; and a solenoid activated valve controllably connected to said thermostatic means whereby the flow of said lubricant from said barrel to said compressor may be automatically controlled.

4. The system of claim 2 in which the automatic valve means is adapted to open upon the reaching of a predetermined tcrnperature in said barrel and to close upon a two degree Fahrenheit drop in temperature below said predetermined temperature.

5. The system of claim 2 wherein the predetermined temperature is at least 15 degrees above the temperature of the ambient air.

6. The system of claim 2 wherein the predetermined temperature is no greater than 20 degrees above the ambient temperature.

7. The system of claim 2 wherein the predetermined temperature is at least 15 but no greater than 20 degrees above the temperature of the ambient air.

References Cited UNITED STATES PATENTS 3,012,414 12/1961 La Porte 62278 FOREIGN PATENTS 818,788 8/1959 Great Britain.

MEYER PERLIN, Primary Examiner. 

1. IN A REFRIGERATION SYSTEM HAVING A COMPRESSOR WITH HIGH PRESSURE AND LOW PRESSURE SIDES AND A CRANKCASE, A HIGH PRESSURE LINE FOR CONVEYING GASES FROM THE HIGH PRESSURE SIDE TO A CONDENSER, A RECEIVER TO COLLECT LIQUEFIED REFRIGERANT IN OPERATIVE RELATION TO SAID CONDENSER, AN EVAPORATOR FOR VAPORIZING SAID LIQUID REFRIGERANT IN OPERATIVE RELATION TO SAID RECEIVER, AND A SUCTION LINE OPERATIVELY CONNECTED FROM SAID EVAPORATOR TO THE LOW PRESSURE SIDE OF SAID COMPRESSOR; THE IMPROVEMENT COMPRISING: A SUCTION LINE EVAPORATOR COMPOSED OF AN ENCLOSED INNER BARREL HAVING UPPER AND LOWER PORTIONS; SAID SUCTION LINE PASSING FROM SAID EVAPORATOR INTO THE UPPER PORTION OF SAID BARREL; SAID SUCTION LINE LEAVING THE UPPER PORTION OF SAID BARREL AND PASSING INTO THE SUCTION SIDE OF SAID COMPRESSOR; A LUBRICANT RETURN LINE PASSING FROM THE LOWER PORTION OF SAID BARREL TO THE CRANKCASE OF SAID COMPRESSOR; AN ENCLOSED JACKET HAVING UPPER AND LOWER PORTIONS SURROUNDING A SUBSTANTIAL PORTION OF THE EXTERIOR OF SAID BARREL; SAID HIGH PRESSURE LINE PASSING FROM THE HIGH PRESSURE SIDE OF SAID COMPRESSOR TO THE UPPER PORTION OF SAID JACKET; SAID HIGH PRESSURE LINE LEAVING THE LOWER PORTION OF SAID JACKET AND CONNECTED TO SAID CONDENSER; TEMPERATURE SENSING MEANS LOCATED ADJACENT THE LOWER PORTION OF SAID BARREL; THERMOSTATIC CONTROL MEANS OPERATIVELY CONNECTED TO SAID SENSING MEANS; AND A VALVE MEANS LOCATED IN SAID LUBRICANT LINE AND CONTROLLED BY SAID THERMOSTAT WHEREBY BY MEANS OF TEMPERATURE SENSING AN AUTOMATIC VALVE CONTROL, LIQUID REFRIGERANTS AND CRANKCASE LUBRICANTS MAY BE SEPARATED AND PASSED TO THEIR RESPECTIVE INLETS IN SAID COMPRESSOR. 